Apparatus for coating interior surfaces of tubular structures



Dec. 13, 1938. s. P. MILLER 2,140,298

APPARATUS FOR COATING INTERIOR SURFACES OF TUBULAR STRUCTURES Dec. 13,1938. s. P. MILLER A Y 2,146,298

APPARATUS FOR COATING INTERIOR SURFACES OF TUBULAR STRUCTURES FiledMarch 18, 1936 3 Sheets-Sheet 2 Dec. 13, 1938. s. P. MILLER APPARATUSFOR COATING INTERIOR SURFACES OF TUBULAR STRUCTURES Filed March 1a,19:56

5 Sheets-Sheet 3 ATTORNEY Patented Dec. 13, 1938 UNITED STATES APPARATUSFOR COATING INTERIOR SUR- FACES F TUBULAR STRUCTURES Stuart P. Miller,Scarsdale, N. Y., assignor to The Barrett Company, New York, N. Y., acorporation of New Jersey Application March 18, 1936, Serial No. 69,481

2 Claims.

This invention relates to coating the interior surfaces of pipes,conduits or other tubular structures and more particularly to anapparatus for coating the interior surfaces of conduits of rel- 5atively large internal diameter, such as penstocks.

One object of this invention is to provide an apparatus and novelprocedure for rapidly and efficiently applying protective material tothe interior surfaces of large tubular structures.

A further object of this invention is to provide a coating machineprovided with self-adjusting rotatable distributors designed to followthe interior surface of the tubular structure and l5 apply and spreadplastic coating material, such as heat liquefied bituminous material,uniformly thereover in bands or ribbons completely covering the interiorsurface of the tubular structure.

Briefly, the apparatus of this invention comprises a frame or carriageprovided with wheels, and having mounted thereupon a tank or containeradaptedto contain hot liquid coating material. A hollow main shaft,which carries adjustable supporting members adapted to rotate in a planeperpendicular to the direction of motion of the carriage, is mountedthereon. One or more distributor nozzles are carried by the adjustablesupporting members. Associated with each distributor is a pad or wiperfor spreading the coating material over the surface of the pipe after itis fed thereon. A guide roller is also carried by each distributor andis arranged to travel on the surface of the pipe or conduit to insuresubstantially uniform clearance between the wall of the pipe or conduitand the distributor or applicator nozzles. The applicator nozzles areconnected to the hollow main shaft by a flexible conduit, the shaftbeing communicably connected with the tank containing the coatingmaterial. As the apparatus moves longitudinally through the pipe,coating material is uniformly and rapidly spread over the interior wallsthereof in the form ofa helical ribbon or band which issimultaneouslysmoothed by the wiper to produce a, uniform, smoothcoating layer.

Alternatively the hollow main shaft may be sufliciently long to projectWithin the pipe while the tank and operating mechanism remain outsidethe pipe but travel in line with` the pipe to`move the rotatingapplicators lengthwise in the pipe. 'I'his is advantageous in treatingrelatively short sections of pipe before assembly. If desired theapparatus may be moved inter- (Cl. Ell-30) mittently through the pipe inorder to apply successive circular bands of coating material instead ofcontinuous helical bands. When operating in this manner, the apparatusis preferably moved a distance substantially equal to the Width of a 5circular band of coating material applied after each complete revolutionof the application nozzles.

In the accompanying drawings in which is depicted by way of illustrationa preferred embodl0 iment of this invention,

Figure 1 is a side elevational View, partly in section, of the coatingapparatus embodying this' invention;

Fig. 2 is an elevational view depicting a modil5 cation of theapplicator mechanism of Fig. 1, in which two pairs of applicators areprovided;

Fig. 3 is a fragmentary elevational detail depicting an applicatormechanism of the apparatus of Fig. 1; 20

Fig. 4 is an elevational View depicting an alternative form ofapplicator mechanism of the apparatus of Fig.` 1;

Fig. 5 is an end elevational view depicting the Way in which a doublelayer of coating material 25v may be applied to the pipe surface by theuse of the mechanism depicted in Fig. 2;

Figs. 6, 8, and l0, are detail views showing in side elevation modifiedforms of applicator nozzles; and 30 Figs. 7, 9, and 11 are endelevational views of the nozzles shown in Figs. 6, 8, and 10respectively.

Referring to Fig. 1 of the drawings, in which like numerals refer tolike parts, the apparatus 35 of this invention comprises a carriage l,provided with a plurality of wheels 2, rotatably disposed on an axleattached to the under side of the floor plate of the carriage. Acarriage having three wheels may be utilized, namely a guide Wheel 3 40situated at approximately the mid-point of the front end (with respectto direction of travel of the carriage when in operation, whichdirection is indicated by the arrow in Fig. 1) of the car. riage and apair of drive wheels 2 at the rear cor- 45 ners thereof. .Guide wheel 3is preferably mounted on a swivel which permits free rotation thereof inthe horizontal plane, and, as will be more fully explained hereinafter,serves' to keep the apparatus traveling along the desired path. 50 Drivewheels 2 are mounted on an axle at the rear of the truck, which axle, aswill be more fully described hereinafter, 's driven so that the wheelsare caused to rotate to cause the carriage .t0 move longitudinallythrough the tubular con- 55 duit. The wheels 2 and 3 are advantageouslyprovided with rubber tires or other suitable tread to prevent damage toprimer or other coating previously applied to inside pipe surface.

Mounted on the carriage is a tank 9 adapted to contain hot liquidcoating material, such as coal tar pitch or other bituminous material.Tank 9 is providedwith heat insulated Walls II) adapted to preventradiation of heat therefrom. A charging inlet II at the top thereofserves as an inlet for fresh coating material, which is maintained inthe molten state therein by a heating unit, preferably an electricalheating unit I2 situated at the base thereof and connecting with asource of current by means of connection I3. The temperature of theliquid mass Within the container may be determined by a thermometer I4which is preferably so placed that the bulb thereof is below the surfaceof the hot material and the scale thereof is on the outside of thecontainer, thus facilitating easy reading. Situated within the containerand adapted to maintain the liquid material therein in a state ofagitation is a stirring device I5 mounted on and rotatably actuated byshaft I6. Shaft I6 is supported Within `the container by bearings I1 andI8 disposed on the walls of the container and extends through bearing I1to the exterior of the container.

A pump I9 of any well known type having an outlet communicatingwith'thepipe 20 is provided for forcing coating material through the pipe. Whilein the illustrated embodiment of the invention pump I9 is shown disposedwithin the tank 9, it will be appreciated that this pump could readilybe disposed exteriorly of the tank.

` If the pump is located outside of the tank it is provided with aninlet projecting into the tank below the level of the coating materialtherein.

A regulating valve 2| disposed in pipe 20 serves to regulate the flow ofcoating material through the pipe.

A standard 5 is mounted on the rear end of the carriage and hasadjustably secured thereto by bolts 6 a bearing member 1 providing abearing 8 extending in a direction parallel to the surface 'of thecarriage. By suitably adjusting member 1 the bearing 8 may be raised orlowered until it is approximately in line with the axis of the pipewhich is being coated. Rotatably mounted in bearing 8 is a main shaft 22extending outwardly beyond the rear of the carriage. The shaft 22 ishollow providing a duct 23 through which coating material flows from thecontainer to the distributing mechanism hereinafter described. Mainshaft 22 is connected to pipe 20 by flexible conduit 24 Which is affixedto the main shaft 22 by a gland member 25 adapted to permit freerotation of the main shaft independently of the connecting conduit` 24.

Extending at right angles to the main shaft 22 and rigidly aflixedthereto by sockets 21 are a plurality of extensible supporting members28 adapted to rotate in a plane perpendicular to the direction of motionof the truck or carriage. Each supporting member 28 comprises a pair ofspaced parallel tubular members 29, preferably of cylindrical shape,having telesoopically mounted therein solid extension members 30 whichare held in position within the hollow members 29 by means of set screws3| and which are connected together at the outermost ends thereof bycross bars 32. By adjusting the set screws 3I the rod members 33 may beextended or retracted to accommodate the distributing mechanism to thediameter.- of the pipe under treatment.

Cross bars 32 have pivotally mounted thereon an applicator ordistributor nozzle. Each applicator comprises a nozzle member 33preferably of metal having a fan-shaped mouthpiece 34 at the end thereofand connected to the main shaft 22 by a exible conduit 35. A valve 31 isdisposed on the line 38 joining flexible conduit 35 to the duct 23 inmain shaft 22. Flexible joints 36 are preferably employed at the pointsof jointure between conduit 35 with nozzle member 33 and conduit 38.

Pipes and fittings between the tank 9 and nozzles 33 may, if desired, beheated, e. g. by means of electric heating coils.

Fig. 3 shows in detail, the construction of an applicator and shows howplastic coating material is spread uniformly over the interior surface58 of a conduit by means of the spreading member 39. Each applicator isattached to the crossbar 32 of the supporting member which, as shown inFig. 3 passes through a hole piercing a lug member 56 formed integralwith or attached to the applicator nozzle 33. Thus the applicator ispivotally mounted onrbar 32 and can move in the plane of rotation of thedistributing mechanism independently of the rotary motion impartedthereto. In this way the applicators adjust themselves to compensate forany unevenness in the surface of the pipe and for slight offcenterposition of the main shaft'with respect to the longitudinal axis of thepipe. The applicator nozzle 33 is maintained at a suitable predetermineddistance from the surface of the pipe by means of a guide roll 40rotatably mounted on an extension arm 6I secured to the applicatornozzle. A spreader 39 is attached to each applicator 33 by rings'51.These spreaders are made of semi-flexible material such as reinforcedasbestos pads, sheet metal or` the like', adapted to permit bending orflexing thereof under tension when forced against the pipe surface. Thislength may be varied ,Pto give a desired wiping effect, depending on theviscosity of the coating material used, the thickness of coatingrequired, etc. In order to maintain spreaders 39 under suitable tensionagainst the pipe surface, a lever arm 62 is provided either integralwith or attached to lug 56, as indicated by reference numeral 63.Tension is applied to the lever arm near the free end thereof by meansof a compressedv spring 64, one end of which is positioned against-'thelever arm and the other positioned against a rod member 65 suitablyattached to extension members 30. As coating material 60 is dischargedfrom the orice of applicator 33, spreading member 39 comes into contacttherevwith and spreads' it evenly over the interior surface of the pipe,as indicated by reference numeral 59. A

A motor 4I, preferably an electric motor, is disposed on carriage I andis in driving engagement with pump I9 and is also adapted to actuate theother moving parts of the apparatus. The motor 4I is provided with adrive shaft "42 which has one end journaled in bearing 43 disposed inwall Ill -of tank 9 and the other end journaled in a bearing, not showncarried by the standard 5. Keyed -to the shaft 42 is a gear 44 whichmeshes with a gear 45, keyed to shaft I6 thus rotating' this shaft andthe stirrer I5 carried thereby. A sprocket wheel 46 keyed to shaft I6has a chain 41 passing thereover which also passes over a sprocket 48keyed to the main shaft 22. The main shaft is thus rotated. Rotarymotion is imparted to the vshaft 52 journaled in suitable bearings, oneof which is indicated by reference numeral 53, by means of a drive chain59 traveling over sprocket Wheel 49 keyed to shaft I6 and sprocket 5Ikeyed to shaft 52. A Worm-gear 54 on shaft 52 is vdisposed to mesh witha gear 55 keyed to the axle carrying wheels 2. Motor III thus driveswheels 2 which cause the apparatus to move. A clutch may be disposedbetween worm-gear 54 and 'shaft 52 to permit placing the worm out ofdriving engagement with shaft 52 so that the motor may operate toagitate the contents of the tank with-out propelling the apparatus. Thegear ratios of the various gear systems used in the apparatus are soarranged that the rate of progress of the carriage through the pipe isslow enough to permit the surface of the pipe to be completely coatedwith protective material. It will be understood that instead of thedrive described above other suitable drives may be employed.

Before applying coating material to the interior surface of a conduit,vthe surface is preferably cleaned by the removal therefrom of any dirtor other materials adhering thereto, and is then primed with a suitableprimer to furnish a bond for the coating compound. The cleaning may beaccomplished by sand blasting the interior or passing a wire brushthereover.

In the operation of the apparatus of this invention, tank 9 is filled.to a suitable level with coating material, such as bitumen, asphalt orpitch, which is maintained in molten condition,

by heat applied thereto from the heater I2. The material is agitatedduring the use of the apparatus by stirrer I5, thus insuring uniformheating of the coating material. The apparatus is inserted in one end ofthe pipe or other tubular structure with the pivoted guide wheel 3 infront. Guide wheel 3 functions to automatically guide the apparatusalong the center of the pipe. The main shaft is adjusted by means ofbolts B until it is approximately in line with axis of the pipe.Applicator arms 28 are positioned by loosening set screws 3l so thatguide roll 40 contacts with the interior surface of the pipe and the setscrews 3| are then tightened to main'- tain the arms in this position.

The motor 4| is then started and the apparatus movedl through the pipe.Pump I9 forces the heat liquefied material to pass through pipe 2D,conduit 24, duct 23, and through the distributor nozzles which apply thematerial in a helical ribbon onto the surface of the pipe. The coatingmaterial may be caused to extrude from as many of the applicators asdesired by suitably adjusting Valves 31. The spreading pads 39, duringthe operation of the apparatus, may be bent under tension against thepipe surface or may be spaced a desired distance from thesurface; e. g.,11g or 1/8 inch etc. to apply a desired thickness of coating to theinterior wall ofthe pipe. Thus, as the coating material leaves thenozzle it is spread uniformly and evenly over the surface of the pipe bythe pressure exerted by the spreaders and spring 64. With thearrangement -of the applicator shown in Fig. 1, upon movement of thecarriage longitudinally of the pipe, the coating material from eachnozzle or applicator is applied to the interior surface of the pipe inthe form of a helix, the bands'of which may overlap to form a continuoussubstantially uniform coating thereon. If the pipe surface is uneven theguide rolls 40 follow the surface and from the pipe surface.

the applicator nozzle 33 pivots about the crossbar 32 to compensate forthe irregularities and to maintain. the nozzle at a definite distanceHence, damage to the apparatus is minimized and frequent adjustments ofthe apparatus obviated, as irregularities encountered are compensatedfor.

The apparatus of Fig. 2 differs from that of Fig. 1 in that two sets ofapplicators or coating distributors 16 and 11 are employed instead ofthe single set shown in Fig. 1. Upon movement` through the pipe at asuitable rate, the apparatus of Fig. 2 will produce a double layer ofcoating material. The rate of application of the coating materialapplied by the apparatus of Fig. 2 is so regulated as to permit thefirst coat applied by the applicators 16 to set before the second coatis applied to the applicators 11. With bituminous coating applied in theheat liquefied condition at a temperature somewhat above the settingpoint thereof, e. g. about 300 to 400 F., the coating sets quickly uponcontact with a cold metal surface, thus permitting relatively rapidmovement of the applicators longitudinally along the pipe withapplication of a double layer of coating material thereto. Each layer isconstituted of a helical band of bituminous material so arranged thatthe respective layers overlap as shown in Fig. 5 ,wherein referencenumeral 18 depicts the bandsfof coating material applied by nozzles 16and reference numeral 19 depicts the superposed bands of coatingmaterial applied by coating nozzles 11. It will be noted the meetinglines of the superposed bands 19 represented by the dark lines on Fig.5, defining the width of a ribbon or band applied by the applicator, areout of alignment with those of bands 18. It is desirable to control therate of movement of the applicators so as to provide the necessary timeinterval to permit the coating applied byV applicators 16 to set beforethe coating from applicators 11 is superimposed thereon.

If desired the apparatus may be operated to apply the coating materialin circular instead of helical bands by connecting the clutch betweenshaft 52 and worm-gear 54 to move the apparatus forward through the pipeonly after each complete revolution of the applicator nozzles. Suitableclutches (not shown) may be provided between motor 4I and pump I9 andbetween gear 45 and shaft 22 to stop the operation of the pump and therevolution of the applicator nozzles while the apparatus is movingforward through the PIPC- Fig, 4- shows an alternative form ofapplicator mechanism. Referring to the drawings, in which the partscorresponding to those of Fig. l have been indicated by like referencenumerals, main shaft 22 extends a short distance beyond bearing 8 andhas pivoted thereto, as indicated by the reference numeral 66, angularlyextending suppprting members 61. Applicator members 33 are fixed at theend of the supporting member 61, as indicated by reference numeral 68.Coating material is conveyed to the applicators 33 by means of flexiblepipes 69 communicating with the main shaft 22 by means of a hollowY-joint 10. A toggle member 1I has the ends 12 pivoted to supportingmembers 61 and is provided with a spring 13 extending across the pivotedjoints 14 of the toggle. The spring 13 tends to force the toggle armscloser together whereby the supporting members 61 carrying theapplicators are moved against the wall of the pipe. Thus, the spreaders39 on the applicators are maintained the supporting members are drawntogether and when in position the supporting members may be permitted tospread so as to move the spreaders on the applicators against the wallsof the pipe under tension provided by spring 13.

The embodiment of the invention illustrated in Fig. 4 is particularlyadapted for uniformly coating the interiors of out of round pipes, i. e.pipes of oval or other non-cylindrical shape. Y It will be observed thatthe spring-tensioned toggle mounting of the applicator nozzlesresiliently presses the rolls 40 into contact with the pipe and allowsthe nozzles to move inwardly and out- Wardly so that they follow thenon-cylindrical contour of the pipe.

' In Figs. 6 and 7 there is illustrated a modified applicator nozzle 13provided with an arm 14 extending along the forward side thereof (withrespect to the direction of movement of the machine through the pipe), aroller 16 journalled in the free end of the arm, and a exible spreadingpad 11. The roller 16 contacts the interior surface of the pipe at apoint behind the outlet of the applicator nozzle (with respect to thedirection of rotation of the nozzle), but somewhat in advance of thefree end of exible pad 11. This embodiment of fthe invention isparticularly adapted for coating pipes having longitudinal welds orother ridges 18 therein. It will be observed that roller 16 and spreaderride over such ridges simultaneously and apply thereto a layer ofcoating material of substantially the same thickness as the layerapplied to the remainder ofi'the pipe.

The applicator nozzle of Figs. 8 and 9 differsy fromV that shown inFigs. 6 and 7 in that flexible pad 11 is provided with a projection 19extending from the forward side of the pad adjacent the free end;thereof. contact with the interior of the pipe and gauges the thicknessof the coating layer applied.

In Figs. 10 and 11 there is shown an applicator nozzle provided with arigid doctor member l8l! extending rearwardly therefrom in lieu of theflexible spreading pads shown in Figs. 1 to 9. 'Ihre free end of thedoctor may be spaced the desired distance from the interior of the pipeto gauge the thickness of the coating layer applied to the pipe by meansof a roller 8| mounted thereon and contacting the pipe. Alternatively,roller 8| may be mounted on an arm extending beside the doctor memberanalogous to the arm illustratedin Fig. 6. The rollers 16 and 8| ofFigs. 6 to 11 are preferably bevelled to enable them to ride readilyover circumferential welds 82 or other circumferential ridges in` thepipe.A

'I'he projection 19 rides in of the pipe. In lieu of two distributingmembers,

any desired number of such members may be employed.

I claim:

l. Apparatus for applying coating material to the interior of tubularstructures comprising a carriage, a tank for coating material on saidcarriage, a vertically adjustable bearing on said carriage disposed nearone end thereof exteriorly of said tank, a hollow shaft rotatablymounted in said bearing and having one end communicably i connected withsaid tank and the other end extending beyond the carriage, an applicatorrotatably mounted on the said other end of said shaft and communicating-therewith and means for sending coating material from said tank throughsaid hollow shaft into and through said applicator.

2. An apparatus for coating the interior surfaces of tubular structurescomprising a carriage adapted to move through the interior of thetubular'structure, a guide wheel supported at the front end of saidcarriage near the mid point thereof, a pair of driven wheels at the rearend of said carriage, a container supported on said' carriage, anagitator within said container, a. pump, a bearing on said carriageexteriorly o'f said container, a hollow shaft rotatably mounted in saidbearing and communicably connected with said container, extensiblesupports on said hollow shaft, flexible applicators carried by saidextensible supports, discharge nozzles o nsaid applicators, a flexiblespreader associated with each discharge nozzle and adapted to uniformlydistribute coating material discharged by the nozzle over the interiorsurface of `the tubular structure, a guide roll carried by the nozzleand adapted to contact with the interior of the tubular structure tomaintain a constant clearance between the discharge nozzle and theinterior wall of the tubular structure, flexible connections betweensaid applicator and said pump, means for rotating said applicator overthe interior of said tubular structure, said means being constructed andarranged to drive said agitator, said pump, and to move said carriagethrough the interior of saidtubular structure.

STUART P. mana.

